Lithium ion batteries are known as an example of batteries with high voltages and high energy densities. Li ion batteries are cation-based batteries utilizing Li ions as the carriers. On the other hand, fluoride ion batteries utilizing fluoride ions as the carriers are known as an anion-based battery.
For example, Patent Literature 1 discloses an electrochemical cell comprising a cathode, an anode, and an electrolyte material that is capable of conducting anion charge carriers and disposed between the cathode and the anode, wherein the cathode and the anode reversibly exchange the electrolyte material with the anion charge carriers during the charge or discharge of the electrochemical cell. In addition, Patent Literature 1 exemplifies fluoride ions (F−) as the anion charge carriers.
Incidentally, Non Patent Literature 1 discloses La1.2Sr1.8Mn2O7 as a compound having a Ruddlesden-Popper structure, although the technology does not relate to a fluoride ion battery.